Prognostic value and relapse pattern of HER2‐low in hormone receptor‐positive breast cancer

Abstract

BackgroundA new concept of HER2‐low has emerged in recent years. However, the prognostic value and the relapse pattern of HER2‐low is unclear.MethodsOur study included patients diagnosed with HER2‐negative/hormone receptor‐positive breast cancer to explore the differences in survival outcomes between the HER2‐low group and the HER2‐zero group. More importantly, we explored different recurrence patterns, including the comparison of metastatic sites and recurrence time curve between the two groups.ResultsA total of 797 patients with hormone receptor‐positive breast cancer were analyzed. Similar disease‐free survival (DFS) was observed between the HER2‐low group and HER2‐zero group (HR 0.84, 95% CI: 0.61–1.16, p = 0.290). There was also no significant difference in OS between the HER2‐low group and the HER2‐zero group (HR 0.77, 95% CI: 0.46–1.28, p = 0.310). When IHC 1+ and 0 were taken as a group, the IHC 2+ group had significantly better DFS than the IHC 1+ and 0 group in some subgroups. The risk of bone metastasis in patients with HER2 IHC 1+ and 0 was significantly higher than that of patients with HER2 IHC 2+ (12.7% vs. 4.7%, p < 0.001). Compared with the HER2‐zero group, we found that the HER2‐low group had a more obvious peak in mortality at the time of postoperative 80th–100th month.ConclusionsNo significant difference in DFS and OS between the HER2‐low group and the HER2‐zero group was observed. Patients with HER2 IHC 1+ and 0 tend to develop bone metastasis. The HER2‐low group had a more obvious second peak in mortality.